1. Field of the Invention
This invention generally relates to a clutch cover assembly. More specifically, the present invention relates to a clutch cover assembly provided with a wear compensating mechanism, which can move a fulcrum of a pushing member toward a friction member by an amount corresponding to an amount of wear occurred in the friction member.
2. Background Information
A clutch cover assembly of a clutch device is attached to a flywheel of an engine. The clutch cover assembly operates to press a friction facing of a clutch disk assembly against the flywheel by an elastic or spring force of a diaphragm spring or the like for transmitting a drive force of an engine to a transmission. Specifically, the diaphragm spring or the like pushes a friction member of a clutch disk assembly against the flywheel for transmitting a drive power of the engine toward a transmission. In this clutch device, when the friction facing of the friction member wears to a predetermined extent or wears beyond the predetermined extent, the friction member can no longer be used. If use of the friction member continues after such predetermined amount of wear, the position of the diaphragm spring of the clutch cover assembly changes to cause disadvantageous change in pushing load. Therefore, the clutch disk assembly must be replaced with a new clutch disk assembly when the wear occurs to the predetermined extent or more. It has been desired to increase the use time of the clutch disk or the replacement cycle, and therefore the lifetime of the clutch.
For increasing the lifetime of the clutch, it is important in the clutch disk assembly to increase an effective service thickness of the friction facing of the friction member in the clutch disk assembly. In view of this increased thickness, the friction facing is fixed to a cushioning plate without using a rivet or the like according to one of several known methods of attachment.
In the clutch cover assembly, it is necessary to return or restore the attitude (orientation) of a spring such as a diaphragm spring to the initial attitude (orientation) when the friction facing of the friction member is worn. For this purpose, the clutch cover assembly is provided with a wear compensating mechanism. The wear compensating mechanism determines an amount of wear of the friction facing. The wear compensating mechanism can move a fulcrum (i.e., a fulcrum ring on the pressure plate side, or a support mechanism on the clutch cover side) of the spring such as a diaphragm spring in accordance with the determined amount of wear. Thereby, the attitude (orientation) of the diaphragm spring or the like can be kept in a constant position or maintained in an initial attitude (orientation) independently of the wear of the friction facing of the friction member. Therefore, the friction facing of the clutch disk assembly can be used to the maximum extent.
In a clutch cover assembly disclosed in Japanese Laid-Open Patent Publication No. 8-170652, a pressing member or a pushing mechanism is formed of a spring and a lever member for applying a pressing force to a pressure plate. The wear compensating mechanism is a mechanism for moving a fulcrum or support mechanism on the clutch cover side toward the friction facing of the friction member in accordance with the amount of wear of the friction facing of the friction member. This wear compensating mechanism is primarily formed of a support member, a biasing mechanism, and a wear detecting mechanism. The support member supports a fulcrum of a lever member on the clutch cover side. The biasing mechanism biases or urges the support member toward the friction member. The wear detecting mechanism detects an amount of friction member wear and allows movement of the pressure plate toward the clutch cover in accordance with the amount of wear.
The biasing mechanism is formed of two ring members having a wedge mechanism with a plurality of inclined surfaces, which are in complementary contact with each other, to form a wedge mechanism, and a spring for biasing the ring member on the clutch cover side in the rotating direction. The spring and wedge mechanism act to move the other ring member and a support member toward the friction member.
The wear detecting mechanism is formed of a cylindrical member, which is axially movably and frictionally engaged with an aperture in the clutch cover, and a bolt which extends from the pressure plate. The bolt has a head in contact with a side of the cylindrical member remote from the friction member. An axial space corresponding to a release stroke of the pressure plate is maintained between the pressure plate and the cylindrical member. The pressure plate is always biased away from the friction member by a plurality of strap plates. When the biasing force of the diaphragm spring is released and therefore the clutch enters the clutch released state, the pressure plate moves away from the friction member, and comes into contact with a friction member side of the cylindrical member.
When the friction member is worn, the pressure plate moves toward the flywheel. Furthermore, the pressure plate moves a bushing relative to the clutch cover by a distance corresponding to the amount of wear of the friction member. As a result, the axial distance between the pressure plate and the cylindrical member is the same as before the wearing of the friction member. When the clutch releasing operation is then performed, the cylindrical member stops the axial movement of the pressure plate. The position where the pressure plate stops is shifted by the amount of wear toward the friction member side from the position before wearing. In other words, the stop position is shifted by a distance corresponding to the wear amount toward the friction member from that in the clutch released state before wearing. Therefore, the axial space corresponding to the amount of wear of the friction member is formed between the pressure plate and the lever member. As a result, the biasing mechanism can move the support member in the axial direction, until the radially outer portion of the lever member comes into contact with the pressure plate when it moves a distance corresponding to the amount of wear.
According to the wear compensating mechanism in the foregoing conventional clutch cover assembly, the amount of wear is detected from the axial space between the pressure plate and the cylindrical member engaged with the clutch cover. The movement and stopping of the support member are performed between the support member and the pressure plate. According to this structure, the pressure plate is moved toward the friction member due to, e.g., vibrations applied thereto in the clutch releasing operation. An excessively large space is then formed between the pressure plate and the support member so that the support member may move a distance larger than the predetermined distance toward the pressure plate. When such over-adjusting occurs, the position of the spring applying a biasing force to the pressure plate changes from the initial state so that the pressing load cannot be constant.
The wear compensating mechanism of the conventional clutch cover assembly is provided with the fulcrum ring for supporting the lever member in addition to the first and second rings. In other words, since the wear compensating mechanism in the conventional clutch cover assembly uses the two ring members, it requires a large number of parts and complicated structures.
In view of the above, there exists a need for a clutch cover assembly which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
One object of the present invention is to provide a wear compensating mechanism, which can move the support member on the clutch cover side for compensating wear of the friction member. More specifically, the wear compensating mechanism is designed to accurately maintain the amount of movement of the support member on the clutch cover side at a desired value.
An object of the invention is to provide a wear compensating mechanism for compensating for wear in the friction member by moving a support member on a clutch cover side. More specifically, the object is to provide a mechanism, which can accurately ensure an intended amount of movement of the support member on the clutch cover side.
An object is to maintain precisely a desired amount of fulcrum movement on a clutch cover side of a pressing member that moves in a wear compensating mechanism.
A further object of the present invention is to provide a clutch cover assembly having a wear compensating mechanism with reduced the number of parts.
An object of the present invention is provide a clutch cover assembly having a wear compensating mechanism, which moves the support member on the clutch cover side for compensating wear of the friction member, while using a fewer number of parts in the wear compensating mechanism.
According to a first aspect of the present invention, a clutch cover assembly is attached to a flywheel for releasably engaging a friction member with the flywheel. The clutch cover assembly of this first aspect of the present invention includes a clutch cover, a pressure plate, a pushing member and a wear compensating mechanism. The clutch cover rotates together with the flywheel. The pressure plate is disposed close to the friction member, rotates together with the clutch cover, but is axially movable with respect to the clutch cover. The pushing member is a member for applying a pushing force directed toward the friction member to the pressure plate. The wear compensating mechanism is a mechanism arranged on the clutch cover, for supporting the pushing member and moving a support position of the pushing member toward the friction member when wear occurs on the friction member. The wear compensating mechanism includes a first inclined surface formed on the friction member side of the clutch cover, and extending in the rotating direction, a first ring member arranged non-rotatably and axially movably with respect to the clutch cover, and having on the clutch cover side a second inclined surface being in complementary contact with the first inclined surface, a biasing member for biasing the first ring member in the rotating direction with respect to the clutch cover to move the first ring member axially away from the clutch cover, and a restricting mechanism being in contact with the friction member side of the first ring member for preventing movement of the first ring member toward the friction member, and allowing movement of the first ring movement toward the friction member when the friction member is worn.
When the friction member is worn in this clutch cover assembly, the restricting mechanism allows the movement of the first ring member toward the friction member by an amount corresponding to the amount of wear. Therefore, the first ring member biased by the biasing member moves toward the friction member. In the above operation, an axial space for allowing movement of the first ring member is formed between the restricting mechanism and the first ring member. Accordingly, even when the pressure plate axially moves due to vibrations supplied thereto during the clutch releasing operation, the shift of the pressure plate does not change the axial space. Thus, an amount of axial movement of a fulcrum of the pushing member can be kept accurate.
According to a second aspect of the present invention, the clutch cover assembly of the first aspect of the present invention further has such a feature that the restricting mechanism has a wear amount detecting member. The wear amount detecting member is axially movably and frictionally engaged with the clutch cover, is in contact with the surface on the friction member side of the first ring member for restricting movement of the first ring member toward the friction member, and moves together with the pressure plate toward the friction member to form a space with respect to the first ring member when the friction member is worn.
According to a third aspect of the present invention, the clutch cover assembly of the first or second aspect of the present invention further has such a feature that the friction compensating mechanism further has a second ring member. The second ring member has a support portion that is in contact with the friction member side of the first ring member, is non-rotatably and axially movably engaged with the clutch cover, and has a support portion for supporting the pushing member.
A clutch cover assembly according to a fourth aspect of the present invention is attached to a flywheel for releasably engaging a friction member with the flywheel. The clutch cover assembly includes a clutch cover, a pressure plate, a pushing member and a wear compensating mechanism. The clutch cover rotates together with the flywheel. The pressure plate is disposed close to the friction member, rotates together with the clutch cover, but is axially movable with respect to the clutch cover. The pushing member is a member for applying a pushing force directed toward the friction member to the pressure plate. The wear compensating mechanism is a mechanism on the clutch cover for supporting the pushing member arranged, and moving a support position of the pushing member toward the friction member when wear occurs on the friction member. The wear compensating mechanism is a mechanism for supporting the pushing member arranged on the clutch cover, and moving a support position of the pushing member toward the friction member by an amount corresponding to an amount of wear when the wear occurs on the friction member. The wear compensating mechanism includes a first ring member arranged rotatably on the friction member side of the clutch cover, and having on the friction member side an inclined surface extending in the rotating direction; a second ring member arranged on the friction member side of the first ring member, non-rotatably and axially movably engaged with the clutch cover, having on the clutch cover side a complementary inclined surface being in complementary contact with the inclined surface, and having on the friction member side a support portion supporting the pushing member; and a biasing member for biasing the first ring member in the rotating direction with respect to the clutch cover to move axially the second ring member away from the first ring member.
In this clutch cover assembly, the first ring member is biased by the biasing member to rotate with respect to the second ring member. Thereby, the second ring member is moved toward the friction member by an axial force applied through the inclined surface. As described above, the wear compensating mechanism is primarily formed of the first and second ring members, and therefore requires fewer parts than the prior art.
According to a fifth aspect of the present invention, the clutch cover assembly of the fourth aspect of the present invention further has such a feature that the wear compensating mechanism further has a restricting mechanism. The restricting mechanism is in contact with the friction member side of the first ring member to prevent movement of the first ring member toward the friction member side, and allows movement of the first ring member toward the friction member side when the friction member wears.
According to a sixth aspect of the present invention, the clutch cover assembly of the fifth aspect of the present invention further has such a feature that the restricting mechanism has a wear amount detecting member. The wear amount detecting member is axially movably and frictionally engaged with the clutch cover, is in contact with the surface on the friction member side of the first ring member for restricting movement of the first ring member toward the friction member, and moves together with the pressure plate toward the friction member to form a space with respect to the first ring member when the friction member is worn.
A clutch cover assembly according to a seventh aspect of the present invention is attached to a flywheel for releasably engaging a friction member with the flywheel, and includes a clutch cover, a pressure plate, a pushing member and a wear compensating mechanism. The clutch cover rotates together with the flywheel. The pressure plate is disposed close to the friction member, rotates together with the clutch cover, but is axially movable with respect to the clutch cover. The pushing member is a member for applying a pushing force directed toward the friction member to the pressure plate. The wear compensating mechanism is arranged on the clutch cover, and supports the pushing member. The wear compensating mechanism is a mechanism for moving the support position of the pushing member toward the friction member side when the friction member is worn. The wear compensating mechanism has a first inclined surface formed integrally with the surface on the friction member facing side of the clutch cover and extending in the rotating direction, a first ring member having a second inclined surface being in complementary contact with said first inclined surface, and being axially movable and rotatable with respect to said clutch cover, and a biasing member for biasing said first ring member in the rotating direction with respect to said clutch cover to move said first ring member axially away from said clutch cover.
In this clutch cover assembly, when the friction member wears, the wear compensating mechanism moves the support position of the pushing member toward the friction member side. This wear compensating operation is performed by the axial movement of the first ring member, which simultaneously rotates with respect to the clutch cover. In this clutch cover assembly, since one of the inclined surfaces of the wedge mechanism is integrally formed with the clutch cover, the whole structure requires a reduced number of parts.
According to an eighth aspect of the present invention, the wear compensating mechanism of the clutch cover assembly of the seventh aspect of the present invention further includes a second ring member. The second ring member is arranged in contact with the friction member side of the first ring member, and is non-rotatably and axially movably engaged with the clutch cover. The second ring member has a support portion for supporting the pushing member. In this clutch cover assembly, when the first ring member axially moves while rotating with respect to the clutch cover for the wear compensating operation, the second ring member axially moves without rotation with respect to the clutch cover. Since the second ring member does not rotate with respect to the clutch cover, the support portion supporting the pushing member does not move in the rotating direction.
According to a ninth aspect of the present invention, the clutch cover assembly of the eighth aspect of the present invention further has such a feature that the biasing member is configured to function between the first and second ring members. In this clutch cover assembly, since the first and second ring members do not axially move relatively to each other, the biasing member functioning between them can stably maintain its attitude.
According to a tenth aspect of the present invention, the clutch cover assembly of the ninth aspect of the present invention further has such a feature that the biasing member is disposed in a space formed between the first and second ring members. In this clutch cover assembly, the biasing member is disposed between the first and second ring members so that the required space can be small.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.